ShUKKI.DT : OsTliOI.OGY OK THK Hl-.KOI HONES. 1 7!> 



jjarapophyses assert thcmscKes. 'I'his is done by a foramen, which 

 exists opposite the nii(hlle of tlie canal in its lateral wall ; this elon 

 gates in the vertebri\; from third to sixth, in a backward direction 

 until it cuts through the hinder and outer margin of the vertebral 

 canal of the sixth vertebra. Then a long pair of i)arapophyses is the 

 result, they being very short and bhuit in the third, fourth and fifth 

 vertebr;\;, and only become sizable in the sixth when overtaken and 

 developed by the advance and breaking through of the foramen in the 

 manner indicated. 



A large covered "carotid canal" is seen in the seventh to the thir- 

 teenth cervical vertebras inclusive; a slight deficiency taking place in 

 the wall of the last, in the median line beneath (A. hcrodias). It is 

 the most anterior part of each of these segments, and they are further 

 characterized by being shorter and stouter than the last four described. 

 The pneumatic foramina of these vertebne are chiefly within the 

 neural canal, piercing its upper wall posteriorly. From the fourteenth 

 to the seventeenth inclusive, these vertebrae are gradually changing in 

 form and character to resemble finally those of the dorsal region. The 

 fifteenth is the first to show a high neural crest, with spreading dia- 

 pophyses at the fore part of the vertebra, while the vertebrarterial canal 

 increases in calibre. 



The neural crests or spines of the seventeenth and eighteenth are 

 thick and long, and interlock \\\\\\ each other by an extensive joint. 



In the ei^^hteenth vertebra we observe for the first time a free pair of 

 pleurapophyses, with very short bodies, but still articulating by tuber- 

 cula and capitula. 



Professor Owen, in speaking of the movement of these vertebra of 

 the cervical region upon one another, says : " This mechanism is most 

 readily seen in the long-necked waders which live on fish and seize 

 their prey by darting the bill with sudden velocity into the water. In 

 the common Heron, for example, {Ardea ci/ierea), the head can be 

 bent forward on the atlas or first vertebra, the first upon the second in 

 the same direction, and so on to the sixth, between which and the 

 fifth the forward inflection is the greatest ; while in the opposite direc- 

 tion these vertebrae can only be brought into a straight line. From 

 the sixth cervical vertebra to the thirteenth the neck can only be bent 

 backward ; while in the opposite direction it is also arrested at a 

 straight line ; from the fourteenth to the eighteenth the articular sur- 

 faces again allow of the forward inflection, but also limit the opposite 

 motion to the straight line." (Anat. of Verts., Vol. ii, p. 39.) 



